Ignition Systems - 1

Most vehicles today use the coil-on-plug type of ignition system. This system involves individual ignition coils for each spark plug, which are directly mounted on top of the spark plugs. This design eliminates the need for a distributor and provides a more efficient and reliable spark delivery to the engine. The coil-on-plug system also allows for better control of ignition timing and improves overall engine performance.

Ignition coils are step-up transformers. They are responsible for converting the low voltage from the battery into a high voltage needed to create a spark in the spark plugs. Step-up transformers have more turns in the secondary coil than in the primary coil, resulting in an increase in voltage. This high voltage is necessary to ignite the fuel-air mixture in the combustion chamber of an internal combustion engine. Therefore, ignition coils act as step-up transformers to provide the required high voltage for the spark plugs.

As engine rpm increases, the ignition timing needs to advance. This is because at higher rpm, the combustion process occurs more quickly, and the spark needs to be initiated earlier in order to achieve maximum power and efficiency. Advancing the ignition timing ensures that the spark plug fires at the optimal moment for ignition, allowing for better combustion and improved engine performance.

Tech A is correct. It is easiest to set the spark plug gap on all the plugs at one time. This ensures that all the spark plugs have the same gap, which is important for consistent ignition and optimal engine performance. On the other hand, Tech B is incorrect in stating that spark plugs come pre-gapped and you should never have to check the spark plug gap. While some spark plugs may come pre-gapped, it is still recommended to check and adjust the gap if necessary, as it can be affected by handling and transportation.

When the driver turns the key to the start position, an electrical connection is made between the vehicle battery and the primary winding of the ignition coil. The primary winding is responsible for receiving the voltage from the battery and creating a magnetic field. This magnetic field then collapses rapidly, inducing a high voltage in the secondary winding. This high voltage is then sent to the spark plugs, igniting the fuel-air mixture in the engine cylinders. Therefore, the primary winding is crucial in the ignition process as it helps generate the necessary voltage for spark plug ignition.

The center electrode is the hottest part of the spark plug because it is the part that is directly exposed to the combustion chamber. When the electrical current passes through the center electrode, it generates a spark that ignites the air-fuel mixture in the combustion chamber. This ignition process creates intense heat, causing the center electrode to reach high temperatures. The ground electrode, insulator, and metal shell also play important roles in the spark plug's function, but they are not directly exposed to the combustion chamber and therefore do not reach the same level of heat as the center electrode.

The correct answer is "required voltage" because it accurately describes the amount of voltage needed to initiate the spark jump across the spark plug gap. This voltage is necessary for the spark plug to ignite the fuel-air mixture in the combustion chamber of an internal combustion engine. The other options, "available voltage" and "induced voltage," do not specifically refer to the initial voltage required for the spark to jump.

Tech A is correct because a defective crankshaft or camshaft position sensor can indeed prevent an engine from starting. These sensors are responsible for providing the engine control module (ECM) with information about the position and speed of the crankshaft and camshaft, which is crucial for proper ignition and fuel injection timing. If these sensors are faulty or not functioning correctly, the ECM may not receive the necessary data to start the engine. However, Tech B is not correct because not all problems with the crankshaft or camshaft position sensor require replacement. Sometimes, the issue can be resolved by cleaning or repairing the sensor, or addressing other underlying issues that may be affecting its performance.

Once the fuel and air mixture has compressed, a spark is needed to ignite the mixture.

It's called waste spark because it fires on a pair of engine cylinders on opposite engine cycles.

The collapse of voltage occurs on the primary side of the ignition coil.

The primary winding of the ignition coil has approximately a few hundred turns of enameled copper wire. This is because the primary winding is responsible for receiving the low voltage from the battery and creating a magnetic field. A few hundred turns of wire are sufficient to generate the necessary magnetic field to induce a high voltage in the secondary winding, which is then sent to the spark plugs for ignition. Having too few turns would result in a weak magnetic field, while having too many turns would increase resistance and limit the flow of current.

Tech B is correct. A secondary ignition shock does not have enough current to kill you. The term "secondary ignition" refers to the electrical system in a vehicle that provides the spark for the spark plugs. While it can deliver a high voltage, it does not have enough current to be lethal. The primary ignition system, on the other hand, which includes the battery and starter motor, can deliver a much higher current and poses a greater risk of electrocution.

Tech A is correct. An ignition coil can be tested using an ohmmeter. An ohmmeter measures the resistance of the coil, which can indicate if there is a problem with the coil. On the other hand, an oscilloscope is not typically used to test the ignition coil. It is used to measure and analyze electrical signals, but it may not provide the specific information needed to diagnose issues with the coil. Therefore, Tech B is incorrect.

The ignition system uses an induction coil to convert low voltage and high current from the battery into high voltage and low current needed to create a spark at the spark plugs. The induction coil consists of two windings, a primary winding and a secondary winding. When the current flows through the primary winding, it creates a magnetic field, which is then collapsed rapidly when the current is interrupted. This collapsing magnetic field induces a high voltage in the secondary winding, which is then sent to the spark plugs to ignite the fuel-air mixture in the engine.

Both Techs A and B are correct. A Hall-effect sensor and an optical-type sensor can both be used in an electronic ignition system. The Hall-effect sensor detects changes in magnetic fields, while an optical-type sensor uses light to detect motion or position. Both sensors can be used to accurately measure the position of the crankshaft or camshaft in an electronic ignition system, allowing for precise timing of the ignition spark.

Ignition coils transform low voltage into high voltage to jump the gap of the spark plug. The secondary side delivers the high voltage to jump this gap.

On an lab scope, the spark voltages as they are read is called a parade pattern.

Both Techs A and B are correct. Tech A is suggesting using a spray bottle and water to test for defective ignition wires, which is a common method. Water can help identify any leaks or faults in the wires by causing them to misfire or create a short circuit. On the other hand, Tech B suggests using a grounded test lead, which can also effectively identify faulty ignition wires. By grounding the test lead and touching it to different parts of the wire, any irregularities or breaks in the wire's continuity can be detected. Therefore, both methods can be used to test for defective ignition wires.

The vehicle speed sensor (VSS) is responsible for inputting vehicle speed.
The cam sensor is responsible for inputting camshaft position to the ECM.